I want to know how can I change my email address/ Account name on guild wars 2?
Because, I have lost this email account and for that reason I need to change it.
And I don’t like more my Account name.
Thank you for your attention.
Regards,

I really encourage you to contact Support by filing a ticket through the “Ask a Question” tab on that linked page. They will be able to assist you or at least answer the question about releasing the account.

For tips on what information to provide in a ticket, please read this post.